A circle is \(360\degree\) or \(2\pi\) radians. We use can a simple proportion to find the correct number of radians.
$$ \frac{2\pi \text{ radians}}{360\degree} = \frac{R \text{ radians}}{630\degree} $$
$$ 2\pi \cdot 630 = 360 \cdot R $$
$$ 1260=360R $$
$$ \frac{1260\pi}{360}=R $$
$$ 3.5\pi=R $$
$$ R= \boxed{\frac{7}{2}}\pi $$
We can do unit conversions as long as we know the conversion, \(\pi\text{ radians}=180\degree\).
$$ 630 \degree \cdot \frac{\pi \text{ radians}}{180 \degree} $$
$$ 630\cdot \frac{\pi}{180} \text{ radians}$$
$$ =\frac{63}{18}\pi $$
$$ = \frac{21}{6}\pi $$
$$ = \boxed{\frac{7}{2}}\pi $$